Desulfonauticus submarinus gen. nov., sp. nov., a novel sulfate-reducing bacterium isolated from a deep-sea hydrothermal vent

Abstract

A novel moderately thermophilic, hydrogenotrophic, sulfate-reducing bacterium, strain 6NT (=DSM 15269T =CIP 107713T), was isolated from matrixes of Alvinella and Riftia originating from deep-sea hydrothermal-vent samples collected on the 13°N East-Pacific Rise at a depth of approximately 2600 m. It was a Gram-negative, non-sporulating, curved rod, motile with one polar flagellum, that did not possess desulfoviridin. It grew at temperatures ranging from 30 to 60 °C, with an optimum at 45 °C, in the presence of 0-5% NaCl (optimum 2%). Strain 6NT utilized only H2/CO2 and formate as electron donors with acetate as carbon source. Sulfate, sulfite, thiosulfate and elemental sulfur were used as terminal electron acceptors during hydrogen oxidation. The G + C content of DNA was 34.4 mol%. Strain 6NT grouped with members of the family Desulfohalobiaceae in the δ-subclass of the Proteobacteria. Its closest phylogenetic relative was Desulfonatronovibrio hydrogenovorans, with only 90% similarity between the sequences of the genes encoding 16S rRNA. Because of significant phylogenetic differences from all sulfate-reducing bacteria described so far in the domain Bacteria, this novel thermophile is proposed to be assigned to a new genus and species, Desulfonauticus submarinus gen. nov., sp. nov.